Aonikasih, the Aonikenk language, it is related to the Selk´nam language, both belonging to the Tshon linguistic branch, which is a different group than that of the rest of the South American hunter-gatherers. (According to Roberto Lehmann-Nistche).

The Aonikaish is composed of approximately 25 basic sounds, six of which are similar to the five Spanish vowels, plus one that is similar to the German ö.

The scholar Spegazzini (1884) describes Aonikaish as follows: "They speak with a very thick voice, vibrating the consonants, very softly, as if they were tired; the throat is used more, as if they were ventriloquists; there are few vowels and only the first syllables may be determined for sure and written, the rest are unintelligible or semi-mute".

For a speaker of this tongue, as the explorer Lista was, the Aonikaish not only had a unique voice for every natural object, it also expresses abstract ideas of a superior order.